Have you tried checking for driver updates for your PC? Open Device Manager and right click on your computer name and click on Scan for hardware changes. This should prompt the installation of any missing driver for your PC if automatically detected.

If no drivers were installed through that method, you may want to visit the website of your PC manufacturer and download the official driver for your Sounds/Microphone system from their downloads page.

For me, my default sound input was changed during the update. I had to reset my microphone as default in the recording sound settings. Also check the Skype settings to make sure it's using the correct input device for microphone.